Mosasaur
Mosasaurs were serpentine marine lizards and ferocious predators. Mosasaurs were not dinosaurs but evolved from semi-aquatic squamates known as the "aigialosaurs", close relatives of modern-day monitor lizards. Mosasaurs breathed air and were powerful swimmers that were well-adapted to living in the warm, shallow epicontinental seas prevalent during the Late Cretaceous Period. They grow up to 17 meters long but the longest ever recorded was 17.5 meters long. Facts Mosasaurs were serpentine marine reptiles. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. These ferocious marine predators are now considered to be the closest relatives of snakes, due to cladistic analysis of symptomatic similarities in jaw and skull anatomies. Mosasaurs were not dinosaurs but lepidosaurs, reptiles with overlapping scales. These predators evolved from semi-aquatic squamates known as the aigialosaurs, close relatives of modern-day monitor lizards, in the Early Cretaceous Period. During the last 20 million years of the Cretaceous Period, with the extinction of the ichthyosaurs and pliosaurs, mosasaurs became the dominant marine predators, however the extinction could have been caused by them. Description Mosasaurs breathed air and were powerful swimmers that were well-adapted to living in the warm, shallow epicontinental seas prevalent during the Late Cretaceous Period. Mosasaurs were so well adapted to this environment that they gave birth to live young, rather than return to the shore to lay eggs, as sea turtles do. The smallest-known mosasaur was Carinodens belgicus, which was about 3.0 to 3.5 m long and probably lived in shallow waters near shore, cracking mollusks and sea urchins with its bulbous teeth. Larger mosasaurs were more typical: mosasaurs ranged in size up to 17 m. Hainosaurus holds the record for longest mosasaur, at 17.5 m. Mosasaurs had a body shape similar to that of modern-day monitor lizards (varanids), but were more elongated and streamlined for swimming. Their limb bones were reduced in length and their paddles were formed by webbing between their elongated digit-bones. Their tails were broad and supplied the locomotive power. This method of locomotion may have been similar to that used by the conger eel or sea snakes today. The animal may have lurked and pounced rapidly and powerfully on passing prey, rather than hunting for it. Mosasaurs had a double-hinged jaw and flexible skull (much like that of a snake), which enabled them to gulp down their prey almost whole, a snakelike habit that has helped identify the unmasticated gut contents fossilized within mosasaur skeletons. A skeleton of Tylosaurus proriger from South Dakota included remains of the diving seabird Hesperornis, a marine bony fish, a possible shark and another, smaller mosasaur (Clidastes). Mosasaur bones have also been found with shark teeth embedded in them. Based on features such as the double row of pterygoid ("flanged") teeth on the palate, the double-hinged jaw, modified/reduced limbs and probable methods of locomotion, many researchers believe that snakes and mosasaurs may have had a common ancestor. This theory was first suggested in 1869, by Edward Drinker Cope, who coined the term "Pythonomorpha" to include them. The idea lay dormant for more than a century, before being revived in the 1990s. In Primeval A fully grown mosasaur attacks a swimming pool lifeguard and kills him. It then returned through the Anomaly that brought it there when the chlorine in the water began irritating its skin. It then appeared at a reservoir in west London and regurgitates a bolus of the undigested remains of the lifeguard. Connor and Abby who had waded out into the reservoir to take water samples where then stalked by the creature. They then rush onto land but are stopped by a high metal fence. Another smaller mosasur comes ashore after them and Connor fights it with an oar. It backs off into the water returns through the anomaly which then closes. It was last seen when Nick Cutter had travelled through the anomaly looking for his wife Helen. He fires a spear at its head, but its skin is too thick to penetrate. It attacks him but only bites down on his scuba, which while leaving him unwounded, also leaves him without air. As the mosasaur swings round for its final attack, the adult mosasaur attacks it, killing it almost instantly and swimming off with its kill. (Episode 1.3) Trivia *Mosasaur means "Meuse (river) lizard". * Seeing as snakes and monitor lizards are very close cousins of these marine equivalents, the Mosasaurs probably did swallow prey whole, as they had no chewing teeth. In support of this, Mosasaurs had a 'second-set', of double-rowed teeth, lining the surface of the upper-jaw (the palate) in the top centre. These are called Pterygoid Teeth. These would have been used like hooks, trapping prey inside the mouth, as well as manipulating the whole prey item into the stomach. It is not a coincidence that these Pterygoid Teeth are found in all snakes and all Mosasaurs. More support comes from the jawbones themselves; they were not connected by any ligaments - and this means that they would have certainly had to eat prey whole. * Mosasaurs became the dominant marine predators, in the last 20 million years of the Cretaceous period (85-65 million years ago) *Very interestingly, as Mosasaurs were very closely related to the Snakes and Monitor Lizards, it is now widely agreed that Mosasaurs had long, forked tongues like their close cousins of the land. Their skulls show that they something called, The Jacobson's Organ. This is a structure used by both Snakes and Monitor Lizards, to detect scent particles in the air or water. Clearly, the Mosasaurs did use this smell detection sense, to hunt their prey, as well as sense the presence of other Mosasaurs of the same species or even family unit. * Having large eyes, Mosasaurs are thought to have had acute eyesight, excellent in the plankton-rich waters of the Late Cretaceous Period. * Some Palaeontologists specialising in Mosasaurs, have hypothesised that Mosasaurs lived in groups, with a possible family organisation centred around the upbringing of vulnerable young. This is an understanderable and convincing idea, as even Mosasaurs were extremely vulnerable as youngsters, (though they could still see off most sharks of the time even as youngsters on the other hand) and this would help to explain why the Mosasaurs were so successful - perhaps they did form groups of individuals that were related, like Whales, for mutual protection, in the most dangerous seas of all time. * Aptly, the name for these possible groups of Mosasaurs, is A Murder, of Mosasaurs! * Not all Mosasaurs were massie-killers; some evolved into comparitatively harmless mollusc-eaters with blunt, crushing teeth. Others, such as Clidastes, and Halisaurus, were much smaller than most Mosasaurs, and preyed on much smaller animals, such as small fish and the now famous, Hesperornis (which featured in Primeval) These 'small-scale' Mosasaurs were likely eaten by their own, larger relatives. *Being so huge, many Palaeontologists believe that female Mosasaurs gave birth to live young at sea, in a similar fashion to the Ichthyosaurs. This is only 'reasonable' spectulation, and it may have been that they somehow slithered and hauled themselves onto flat and open beaches, laying eggs in the sand, burying them with their flippers, and then promptly returning to water. This may not be possible as it is for living sea-snakes, (which are very similar to Mosasaurs) but it is a tempting possibility. *The full grown adult Mosasaur was the biggest creature on the show until the appearance of the Giant Scorpion in Episode 2.5. Errors *Mosasaurs were smooth and streamlined; the one depicted is covered in Crocodilian armor. Gallery Mosasaur2.jpg P.Mosasaur .jpg mosasaur_1.jpg Category:Squamates Category:Cretaceous creatures Category:Series 1 Creatures Category:Creatures Category:Creatures that cause deaths